Modern unleaded gasolines, after combustion, leave deposits on various components of internal combustion engines. Evidence of these deposits may be seen by inspecting the tailpipe or opening the throttle blades and using a light to visually inspect the visible portions of the intake system. Many of these deposits are controlled by adding detergent compounds to the gasoline. Generally speaking, super unleaded fuels contain a higher concentration of this detergent additive which may provide a reasonable job of control of undesired deposits in the intake system. For these detergent additives in the fuel to remove deposits from various parts of the engine, they need to be sprayed on the parts that require cleaning. This cleaning action of the fuel additives performs reasonably well on throttle body style fuel injection systems as the fuel is sprayed at the initial point of air flow into the engine which allows detergent compounds within the fuel to maintain the intake system in a reasonably clean condition.
This is not the case with port fuel injection system engines. This type of system sprays fuel directly in the air stream just before the intake valves. As a result, the components in the intake manifold from the air intake down to the point where the fuel injectors spray the fuel are subject to formations of unwanted deposits from oil from the crank case ventilation system and exhaust gases from exhaust gas recirculation systems. These deposits contribute to form a "dirty" intake system. No matter what brand or quality of fuel is used or how often the fuel injectors are cleaned or which additives are used, they will not eliminate these deposits as the cleansing action of the detergents contained in the fuel are not applied to the components that are located upstream of the fuel injectors.
Most modern engines contain many components in the path of air flow into the engine that are affected by these deposits. These components include: intake valves, fuel injector nozzles, idle air by-pass valves, throttle plates, exhaust recirculation valves, air charged temperature sensors, knock sensors, air flow meters, turbo chargers, and safety valves. Not all of these components are present in all engines.
Deposits on these components can result in a wide variety of driveability complaints with the most common problems being unstable idle speed control and stumbling when cold.
In addition, deposits on the intake valves act like sponges and absorb fuel which degrades cold starts. Intake valve deposits also restrict air flow, reducing both low speed and high speed performance. Current fuel additives are not completely successful in minimizing or eliminating deposits on the intake valves.
The normal method of cleaning intake systems and intake valves is to partially or completely disassemble the engine. The intake manifold is removed from the engine. All components are removed from the manifold and cleaned or replaced. The intake manifold is cleaned. The head is removed from the engine. The valves are removed from the head and cleaned or replaced. The engine is then reassembled. This, of course, is time consuming and expensive.
Another method to clean the intake valves is to remove the fuel injectors, insert a sandblasting tip, and blast the intake valves, in place, with a blasting media such as crushed nut shells. This is not completely satisfactory because of uneven cleaning and the difficulty in removing the residue of the crushed nut shells.
A need, therefore, exists for a method and apparatus to clean the intake system of an internal combustion engine without disassembling the engine.